Electrosensitive facsimile stencilforming blanks



H. R. DALTON Nov. 8, 1966 ELECTROSENSITIVE FACSIMILE STENCIL-FORMINGBLANKS Filed Feb. 18, 1964 2 Sheets-Sheet l M wmwuwmwfim u 1! m iurr @ma X usiwwwwnk 93 n {Ev Mo uuu m H. R. DALTON Nov. 8, 1966ELECTROSENSITIVE FACSIMILE STENCIL-FORMING BLANKS r 1 N R WA o ND 5 AA.a 0 A e mm z fl 2 M K Filed Feb. 18, 1964 United States Patent 3,283,704ELECTROSENSITIVE FACSIMILE STENCIL- FORMING BLANKS Harold R. Dalton,Jenkintown, Pa., assignor to Timefax Corporation, New York, N.Y., acorporation of New York Filed Feb. 18, 1964, Ser. No. 345,762 1 Claim.(c1. 101-128.2)

This invention is a continuation-in-part of US. application SN 658,074,filed May 9, 1957 (now abandoned) and relates to stencil-forming blanks,and more particularly it relates to blanks which are electrosensitive toapplied electric signals to produce a perforated stencil record of suchsignals.

Another object is to provide an electrosensitive facsimile recordingblank which consists of a normally non-conductive plastic film which haspowdered carbon homogeneously distributed through the body of theplastic and which has also embedded in the plastic a sheet of foraminousmaterial such as a finely woven fabric having retic-ulations or openingsof uniform dimension, which openings are bridged by the said conductiveplastic.

Another object is to provide an electr-osensitive stencilforming blankwherein the body of the blank is constituted of a conductive layer whichis substantially free from fibrous stock such as Yoshino paper and thelike.

Another object is to provide an improved electrosensitive film which canbe perforated under control of applied electric voltages to produce ascreen which is useful in any silk screen printing or duplicatingprocess.

A feature of the invention relates to a novel electrosensitivestencil-forming blank which has strata of different electricconductivities, at least one of the strata having embedded orincorporated therein a foraminous sheet or film having perforations ofuniform dimension so as to impart more precise perforation .of the blankin minute areas under control of stylus applied electric voltages.

A further feature relates to an electrosensitive stencilf-orming blankcomprising a backing member to which is strippably attached with a lowdegree of adhesive affinity a film consisting of conductive plastic ofgraded or stepped conductivity considered through the thickness of thefilm, one portion of the plastic thickness having embedded orincorporated therein a foraminous sheet such as a fine mesh silk fabricor the like.

A further feature relates to an improved silk screen stencil.

A still further feature relates to the novel organization, arrangementand relative location and composition of parts which cooperate toprovide an improved facsimile recording blank.

Other features and advantages will be apparent after a consideration ofthe following detailed descriptions with the attached drawing and theappended claim.

In the drawing:

FIG. 1 is a top plan view in magnified form of a section of a blankaccording to the invention;

FIG. 1a is a highly magnified sectional view of FIG. 1, taken along theline 1a1a;

FIG. 2 is a schematic diagram of an organization of apparatus for makingthe blank of FIG. 1;

FIGS. 3, 4, and 6 are magnified sectional views taken, respectively,along the lines 3-3, 44, 5-5, -6-6, of FIG. 2;

FIG. 7 is a composite sectional view of a blank and method ofperforation according to the invention;

FIGS. 8 and 9 are magnified cross-sectional views of modifications ofthe blank according to the invention;

FIG. 10 is a schematic diagram of, another organization of apparatus formaking the preferred form of the blank;

FIGS. 11-15 are cross-sectional views taken along the respectivelyidentified cross-section lines of FIG. 10;

FIG. 16 is a magnified cross-sectional view of the preferred form of theblank;

FIG. 17 is a magnified cross-sectional view of a modification of FIG.16;

FIG. 18 is a magnified cross-sectional view of a further modification ofFIG. 16.

The present invention provides an electrosensitive signal recordingblank such as is generally used in facsimile reproduction systems, andis in the nature of an improvement on the kind of blank disclosed in myprior Patent No. 2,664,043, although in certain of its aspects theinvention is not limited to that general kind of blank. One form of theblank according to the invention is shown in highly magnified top planview in FIG. 1, and in highly magnified sectional view in FIG. 1a and inFIG. 6.

The blank comprises a unitary composite sheet consisting of a speciallyprepared conductive plastic 10, such for example as any of the wellknown vinyl resins of which vinyl chloride-vinyl acetate copolyniers,vinyl chloride polymers, vinylidine chloride copolymers, styrenepolymers, are typical. Integrally embedded in part of the blankthickness, preferably so as to be substantially entirely below the uppersurface of the plastic film, is a sheet or film 11 of foraminousmaterial. The material 11 is preferably of a woven, knitted, matted ornetted fabric of silk, cotton, nylon, Dacron, rayon, or other natural orsynthetic fibre. That is to say, the fabric should have mesh openingswhich are of substantially uniform size and distribution and extendsubstantially uniformly transverse to the surface of the fabric. Sincethe size of the mesh openings to a certain degree controls the finenessand uniformity of electrical perforation of the blank, as will bedescribed hereinbelow, preferably, although not necessarily, the meshshould be equivalent to a woven fabric having for example to 400 threadsper inch, the threads being approximately one to several thousandthsinch in diameter.

In one form shown in FIGS. 1 and 6, the plastic may be formed in twosuccesive passes to form two strata 10a, 10b, with the stratum 10a byitself being of much lower electric resistance than the stratum 10b byitself. Of course when the plastic film 10 as a whole is made by thetwo-pass process, the two strata 10a and 1% are compatibly bonded toform, in effect, a unitary film having the desired combined electric.conductivity through the film thickness. Thus, by way of example, thestratum 10a may have a dry thickness of approximately 0.0002 inch to0.0008 inch, with a surface electric resistance in the film ofapproximately 500 to 2000 ohms as measured between contacting surfaceelectrodes, as described in my prior Patent 2,664,043. The stratum 101)may, for example, have a dry thickness of approximately 0.0005 inch to0.005 inch. The combined thickness of the stratum 10a and stratum 1012with the foraminous sheet 11 embedded therein, need not exceed 0.006inch and the combined surface resistance of the two strata when measuredby two electrodes spaced apart one centimeter, as described in Patent2,664,043, may be between 500 and 1,000,000 ohms. The foraminous sheetor film 11 may be embedded or incorporated in the stratum 10b of lowerconductivity. However, under certain circumstances the forarninous sheetor film may be embedded or incorporated in the stratum 10a of higherconductivity, as shown in the magnified cross-sectional view of FIG. 8,or it may be incorporated in an additional stratum as shown in FIG. 16.

One of the advantages of a blank according to the invention, over theprior blank as shown in my prior Patent 2,664,043, is that by reason ofthe iow stretch and ing as compared with paper stock blanks.

are applied to the stylus 15.

high tensile strength of the foraminous sheet 11 which forms an integralembedded part of the blank, the blank as a whole is free fromundesirable stretching or dimensional distortion during handling orstripping. In such a facsimile blank which does not contain the embeddedforaminous or woven fabric, since the plastic blank requires thepresence of softening agents during its manufacture, the plasticpossesses a considerable degree of stretchability somewhat similar torubber film. Such stretchability .is undesirable in certain fields ofutility. Furthermore, by incorporating the uniformly foraminous wovenfabric 11 in the conductive plastic, the blank is substantially freefrom non-uniform stretching and is less likely to be destroyed byaccidental ripping, tearing, or the like. This is particularly true whenthe blank is attached in a strippable manner to a backing sheet fromwhich it is to be stripped after the electrical perforation of theplastic blank has been effected.

Another advantage over the prior electrosensitive blanks of the kindwhich rely on a paper or fibrous stock, such as Yoshino paper, is theability to control the per unit area conductivity with more uniformprecision. F urthermore, the plastic is essentially non-absorbent tomoisture as compared with paper stock. Also it has a higher order ofanti-creasing since the incorporation of the plastic, which isessentially an elastomer, enables the blank to be handled and storedwithout too much danger of creas- Furthermore since the blank is ineffect a continuum of plastic in a foraminous non-fibrous base, itsmechanical resistance to wear, tear and the like is substantiallyincreased.

Since the over-all thickness of the blank is relatively small, forexample of the order of approximately 0.006

inch, the likelihood of ripping or dimensional distortion is greatlyreduced by the inclusion of the foraminous fabric 11, and the blankremains in a perfectly flat shape and free from the tendency to curl,buckle, or assume other non-fiat shape. Since the blank is designedespecially to be perforatably responsive to applied point-like electricdischarges, its electrical conductivity is of great important ascompared with the conventional silk screen stencil designed to beperforated by mechanical or chemical means. Accordingly the blank isespecially designed for use in any conventional electric facsimilerecording machine employing a needle or similar pointed styluselectrode. Thus, as shown in FIG. 7, the blank of FIGS. 1, 6, 8 and 9can be supported on a suitable conductive mem=ber 12 which may take theform of the grounded metal platen or metal drum of any well knownfacsimile recording machine 13.

The drum 12 may, by any conventional means, he rotated around its axisat a predetermined scanning rate so as to be synchronized with a similarscanning drum at any conventional facsimile transmitter, whichtransmitter constitutes the source 14 of the facsimile electric signals.These signals are received and amplified and applied to a needleelectrode or stylus 15 which is arranged to be moved along the length ofdrum 12. In other words,

the lights and shades of the successive elemental areas of the subjectmatter at the transmitter are converted by well known facsimile methodsinto electric signals which As a result of the electric conductivitycharacteristics of the blank 10', it becomes perforated through itsthickness, as indicated by the nu- -meral 16. These perforations are ofminute cross-section and may be as small as 0.0005 inch in diameter.

One of the problems encountered in making conductive plastic blanks isto insure that the blank has, for

an applied electric signal voltage of a given amplitude, .uniformperforatability over its entire recording surface.

I have found that by incorporating the uniform foraminous sheet or film11 in the body of the conductive plastic act to prevent undesirablemushrooming of the discharge away from the very minute area beneath thepoint of the electrode 15. Therefore, by making the openings 17 ofextremely minute size it is possible to perforate the blank in moresharply confined regions beneath the stylus. Furthermore, with such ablank the danger of the blank being cut out along a continuous line as aresult of a continuous discharge moving along the surface of the blankis avoided, since only the plastic portion of the blank is perforated bythe signals. The unrecorded reminder of the blank remains intact, thuspreventing a completely continuous slit being formed.

It will be understood, of course, that in the -art of facsimiletransmission and reproduction, the signal voltages used for recordingare of a relatively low value, for example of the order of 200 to 500volts. For that reason there is a practical limit to the over-allthickness of the blank for satisfactory recordings, which thickness neednot be substantially greater than 0.006 inch. Furthermore, because ofsuch thickness limitations, the highly conductive stratum 10a is usuallyof extreme thinness, for example between 0.0002 inch and 0.0008 inch. Inthat case it is not feasible to embed the foraminous material or film 11completely in the highly conductive stratum 10a. Preferably, therefore,the lower conductivity stratum 10b can be made slightly thicker than thestratum 10a so as to facilitate the embedding of the foraminous fabric11 therein and so as not to cause any substantial part of the fabric toproject above the upper surface of the stratum 1%. If desired, insteadof using paper or other similar insulating material for the backing 20,that backing may be of conductive material to which the blank isstrippably attached. For example as shown in cross-section in FIG. 9 theblank can be strippably attached to a metal foil backing 32. Thisenables the backed blank to be packed or stored more conveniently, andafter the composite plastic-foraminous screen blank proper has beenperforated by the facsimile signals, it can be readily manually strippedfrom its backing for use in any well known silk screen or othermultireproducing system. When the recording takes place with either thepaper backed blank or the metal foil backed blank, only the blank properis perforated, the backing remaining unperforated. But when the blank isstripped from its backing the latter carries a duplicate carbon recordof the signals. However, the blank can be recorded on without thebacking sheet.

Referring to FIG. 2 there is shown in schematic form one method ofmanufacturing the backed blank. The backing material 20 in the form of asmooth-surfaced paper or metal foil, cardboard, or plastic web, is drawnoff a supply reel 21 and is supported on an endless belt or conveyor 22which is driven in the direction of the arrow, thus carrying the backingweb 20 towards the receiving reel 23 which may be driven at the samerate of speed as the conveyor 22. If the web 20 has its smooth densesurface on one side only, the web is unreeled from the reel 21 with thatsmooth surface uppermost.

The web 20 passes the discharge opening of any well known applicatordevice 25 which contains the plastic 10a in liquid form so as to applyto the smooth surface of web 20 a film of that plastic which when drywill have the required thickness, for example of 0.0002 to 0.0008 inch.It will be understood, of course, that the device 25 is merelyschematically representative of any well known coating mechanism,whether of the roll, brush, spray or knife coating kind, for applyingthe requisite metered film of conductive plastic 10a to the backing web20. The web 20 carrying the coating 10a is then subjected to any heatingor drying operation represented schematically by the dryer 26, so as toleave a dry coating 10a on the backing. The coated backing is thencarried past another coating device 27 which may be similar to thedevice 25, for applying the conductive plastic film 10b over the dryfilm 10a. Immediately after being coated with the film b, and while thelatter is still in a liquid or semi-liquid condition, a web of theforaminous film or fabric 11 from a suitable supply roll 28 is laid onthe coating 10b and, if necessary, it may be subjected to a lightrolling pressure by suitable pressure rolls 29, 30 so as to embed thefabric 11 into the body of the viscous plastic film 10b.

The composite backing with the two plastic coatings is then subjected toanother heating or drying operation represented schematically by thedryer 31. The dried composite material comprising the backing 20 and thetwo hardened conductive plastic and fabric coats 10a, 10b (and 11) arethen reeled on the receiving reel 23. The reel 23 can be stored and thecomposite backed plastic blank can be cut into suitable lengths or sizesby any well known cutting device (not shown).

If desired, prior to reeling the composite blank on the reel 23, theexposed upper face of coating 10!) may be provided with a maskingcoating of contrasting shade with respect to the coating 10b. Thismasking coating may be of the kind disclosed in US. Patent 2,664,043 andis merely of sufiicient thinness to provide a lightcolored appearance tothe upper surface of the blank. By upper surface is, of course, meantthat surface of the blank which is adjacent the recording stylus (FIG.7). Thus the recording can be visually observed during the recordingoperation.

While the blank can be manufactured with a backing strippably attachedthereto, it will be understood that the invention is not necessarilylimited thereto. For example the blank consisting of the strata 10a,10b, with the embedded foraminous fabric 11, may be cast or coateddirectly onto the surface of the conveyor belt 22, that is, without thepaper backing 20. The belt 22, of course, will be of a suitable materialsuch as stainless steel or other hard smooth surface material from whichthe dried composite plastic-foraminous fabric blank can be stripped.

While in the foregoing embodiments, the foraminous fabric isincorporated or embedded in either the low conductivity stratum 10b(FIGS. 1:: and 6), or in the high conductivity stratum 10a (FIG. 8), Ihave found that, if desired, the foraminous material can be incorporatedin a third conductive plastic stratum. In any case, the particularstratum of plastic into which the foraminous material is incorporated,as shown in FIGS. 1a, 6 and 8, is, preferably, approximately equal tothe thickness of that stratum. Thus as shown in FIGS. 1a and 6, theforaminous material 11 has a thickness which is approximately the sameas the thickness of the stratum 10b, whereas in FIG. 8 the foraminousmaterial 11 has a thickness which is approximately the same as thethickness of the stratum 10a.

I have found that for certain applications when the foraminous materialor fabric is completely embedded in or otherwise bonded to that stratumwhile the latter is viscous, it is not always possible to controlprecisely and maintain the desired uniform con-ductivity of thatstratum. I have also found that improved characteristics are obtained inthe finished blank if, instead of embedding or incorporating theforaminous fabric or material directly in the low conductivity stratum1%, it is incorporated or embedded partially or wholly in a thirdstratum which is applied separately to the stratum 10b. The conduc- .itdoes not disturb or change the predesigned uniform conductivity orresistance of the stratum 1012. Such a .typical blank is shown inmagnified cross-sectional view ,in FIG. 16.

It may consist of the paper or cardboard 6 backing 20 with the highconductivity stratum 10a, the low conductivity stratum 10b and with athird stratum 10c11.

Referring to FIG. 10 there is shown in schematic form a preferred methodof manufacturing the preferred blank shown in FIG. 16. The partsillustrated in FIG. l10 which are similar to corresponding parts of FIG.2, carry the same designation numerals. In the arrangernent of FIG. 10there is an additional applicator device 33 which contains theconductive plastic in liquid form. The material 10c is applied on thestratum 10b after this latter stratum has been dried by passage throughthe dryer 26a thus forming a third conductive stratum 10c. Immediatelyafter application of the stratum 10c and while the latter is still in aliquid or semi-liquid condi tion, a web of the foraminous fabric or film11 is fed from a supply roll 28 and applied to the viscous stratum 10c.The foraminous material 11 may be lightly laid or lightly pressed intothe viscous stratum 10c by a light pressure guide roll 29. The compositeassembly is then dried in a suitable dryer 31 to permanently bond theforaminous material 11 to the assembly. This assembly 35 is preferablyleft on the backing 20 until after the blank has been recorded. However,if desired instead of using a paper backing 20 for the blank, theconveyor belt 22 may be of a dense smooth surface material such asstainless steel or the like. In that case, the paper backing 20 and itssupply reel 21 can be omitted. Thus the stratum 10a can be applieddirectly on to the surface of the conveyor 22. After this compositeassembly passes the dryer 31, it can be stripped from the conveyor 22 byany well known stripping device, schematically represented by thenumeral 36.

Preferably the thickness of the composite stratum (10c, 11) is such thatit does not materially increase the thickness of that composite stratumbeyond the thickness of the'foraminous fabric or film 11 itself. Thiscondition is illustrated in the cross-sectional view of FIG. 16 whereinthe openings in the material 11 are shown as filled with the conductiveplastic 100. It is not necessary that these openings in the material 11be completely filled to the surface of the fabric as long as theconductive plastic 10c bridges the walls of the respective openings inthe foraminous material. This relation is shown in the highly magnifiedcross-sectional view of FIG. 17 wherein the foraminous fabric or fihn 11has its openings 37 bridged by the conductive plastic 10c, but thethickness of this plastic in each opening is somewhat less than thethickness of the foraminous materal 11.

Merely by way of example, the stratum 10a may have a dried thickness of0.0002 inch to 0.0008 inch and it may have a surface resistance of from500 ohms to 2,000 ohms. The stratum 10b may, for example, have a driedthickness of approximately 0.0005 inch to 0.005 inch and may have asurface resistance of from 500 ohms to 1,- 000,000 ohms. Likewise, thecomposite stratum (10c, 11) may have a thickness of approximately 0.0001inch to 0.003 inch. Or stated in terms of the foraminous fabric ormaterial itself, the composite stratum (10c, 11) may have a thicknessequal to the thickness of the material 11 or slightly more than thethickness of the material 11 and it may have a surface resistance offrom 500 ohms to 10 megohms.

The finished composite blank assembly, a portion of which is shown inmagnified cross-sectional view in FIGS. 15 and 16, therefore consists ofthe backing 20 to which is adherent in a readily strippable manner, thecomposite assembly or web 35 comprised of the highly conductive basestratum 10a, the lower conductive stratum 10b, and the composite stratum(10c, 11). This assembly 35, as hereinabove described, forms a unitaryweb or film, for example, of 0.008 inch total thickness which can bereadily stripped from the backing 20. Prior to stripping from thebacking 20, the blank can be recorded upon in transversely to thesurface of the fabric.

7 the manner described above in connection with FIG. 7 as a result ofwhich the blank assembly 35 is perforated by the recording signals andthus forms a duplicating stencil which can be stripped from the backing2.0.

The invention is not limited to any particular kind of resin that may beused for the coating batches 10a, 10b, 100. These batches may be any ofthe vinyl resins of which vinyl chloride-vinyl acetate copolymers, vinylchloride polymers, vinyl vinylidine chloride copolymers, styrenepolymers, etc. are typical. The material 11 is preferably of a woven,knitted, matted or netted fabric of silk, cotton, nylon, Dacron, rayon,or other natural or synthetic threads and preferably formed frommonofilament threads. The fabric should have mesh openings whichpreferably are of substantially uniform size and distribution and extendsubstantially, uniformly, Since the size of the mesh openings inmaterial 11 may, to a certain degree, control the fineness anduniformity of electrical perforation of the blank, preferably, althoughnot necessarily, the mesh should be equivalent to a woven fabric having,for example, 100 to 400 mono-filament threads per inch, the threadsbeing approximately one to several thousandths inch in diameter. In anyevent, the fineness 'of the mesh should be correlated with the finenessof the perforation recordings to be effected in the blank. For

example, the mesh may be correlated with the size and spacings of therecorded perforations so that when copies are made from the stencil theyapproximate the quality of the usual rotogravure half-tone reproduction.It should also be understood that the invention is not limited to 'thematerial 11 being a woven fabric.

It may be in the form of any well known uniformly perforated film havingthe desired tensile strength equivalent to that of a woven fabric asdistinguished from paper materials such as Yoshino paper and the like.

One of the advantages of the blanks hereinabove described is that byreason of the low stretch and high tensile strength of the material 11which forms an integral part of the finished blank, the blank as a wholeis free from undesirable stretch or dimensional distortion duringhandling or stripping. It also has important advantages over the priorblanks using a paper base such as Yoshino paper. Since the overallthickness of the conductive film portion of the blank is relativelysmall, for example, in the order of 0.006 inch, the likelihood ofripping or dimensional distortion is greatly reduced and the blankremains in perfectly flat shape and free from a tendency to curl,buckle, or assume other non-fiat shape. Since the blanks are designedespecially to be perforatably responsive to applied point-like electricdischarges, their electrical conductivity is of the essence as comparedwith the conventional silk screen stencil which is designed to beperforated by mechanical or chemical means. The blanks according to theinvention are especially designed for use in any conventional electricfacsimile recording 11 of extremely minute size, it is possible toperforate the blank in more sharply defined elemental regions beneaththe recording stylus. Furthermore, the danger of the blank being slitalong a continuous line as a result of a continuous discharge movingalong the surface of the blank is avoided since only the conductiveplastic portion of the blank enclosed within the foraminous openings ofmaterial 11 therein are perforated by the signals. The remainder of theblank between the recorded perforations remains intact, thus preventinga completely continuous slit being formed.

It will be understood, of course, that in the art of facsimiletransmission and reproduction the signal voltages used for recording areof a relatively low value, for example, to the order of 200 to 1,000volts. For that reason there is a practical limit to the overallthickness of the conductive portion or assembly 35 of the 'blank forsatisfactory recordings and this thickness need not be substantiallygreater than 0.006 inch. After the blank has been recorded upon by beingperforated it can be used in any well known silk screen or othermulti-reproducing system, such for example as illustrated in US.

Patent No. 3,081,698.

As hereinabove pointed out, the strippa-ble backing for the blankinstead of being of paper or cardboard 20 may be of metal foil 32, asillustrated in FIG. 9. While FIG. 9 shows the foraminous material 11incorporated in the stratum 10b, the blank of FIG. 9 may be modified asillustrated in FIG. 18, so that the metal foil backing 32 acts as a highconductivity stratum to which is applied the low conductivity stratum10b and then there is applied to the stratum 1011 a composite stratum(10c, 11).

While in the foregoing it has been mentioned that the foraminousmaterial or fabric 11 has been applied directly to the viscous material10c, if desired, the foraminous fabric or material 11 may be prepared inany well known manner so that the filaments thereof are pre-coated withany suitable conductive material such as the same material for the batch10c but without substantially filling the pores of the fabric. In otherwords, even though the fabric 11 is thus pre-treated, when it is appliedor lightly laid on the viscous stratum material 10c, the fabric musthave sufficient porosity to enable the solvents of the stratum to 'beremoved in the dryer 31 by passage through the pores of the pre-treatedfabric.

Inasmuch as the various form of blanks hereinabove described containpowdered carbon as the conductive ingredient, the upper surface of eachblank will therefore have a blackish appearance. If desired, thisblackis-h surface may be coated with a thin masking coating of asuitable whitish masking material containing a whitish pigment such aszinc oxide, zinc sulfide in a suitable binder, or any other well knownmasking coating such as described, for example, in my prior Patents2,554,017 and 2,664,063. Merely for simplicity, this masking coating isindicated 'by the numeral 38.

While in the foregoing reference has been made to the foraminous film 11as being of silk or other natural or synthetic fabric which is formed ofinsulating strands, for certain applications the film 11 may be formedof metal mesh of the desired fineness and porosity above noted. It mayalso be a metal foil which has been perforated by any well known processto provide a multiplicity of uniformly distributed perforations. Theseperforations should have the fineness and spacing equivalent to the meshhereinabove referred -to.

While the expression silk screen has been used here-. in, it will beunderstood that it is used in the generic sense employed in the silkscreen printing art, to include a screen constituted either of silk orother openwork mesh fabric, which may be formed of non-conductivestrands or of conductive strands such as fine mesh metal cloth.

While various values, materials and proportion of parts have beenmentioned herein, it will be understood that they are given merely forexplanatory purposes and not by way of limitation on the claim attachedhereto.

What is claimed is:

An electrosensitive blank for producing a record of electric voltagesapplied thereto, comprising a sheet of a continuous, self-sustaining,non-conductive, organic plastic, said sheet having a continuous plasticfinish on its opposite surfaces, a non-conductive, foraminous member of100 to 400 mesh incorporated in said sheet, said foraminous memberhaving openings of uniform dimension, said sheet having powderedconductive particles 9 distributed throughout the body thereof to renderthe blank as a whole responsive to said voltages to make a permanentperforated record thereof.

References Cited by the Examiner UNITED STATES PATENTS 1,194,899 8/1916Strippel 101-1282 X 1,606,217 11/1926 Gestetner 101-128.2

Brush 117--128 Koreska et a1. 101426 X Nichols 101-128.2 Meigs 101-426 XDalton 101--426 X DAVID KLEIN, Primary Examiner.

WILLIAM PENN, Examiner.

